Patent GB-659384-A (GB)
Title: Improvements in or relating to a device for determining the weight of a supported load
IPC: G01G19/18
Filed: 1949-10-19
Abstract: 659,384. Lifts. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Oct. 19, 1949, No. 26869. Convention date, Nov. 19, 1948. [Class 78 (iii)] [Also in Groups XVIII and XXXVII] A device for determining the weight of the load supported by a lift car comprises a number of rods 9a-9f connected with the ends of the hoisting cables and individually displaceable against counter-balancing springs 105a- 105f by the tension in the separate cables, a flexible chain 21 the path of which is determined by rollers 131a-131f which are arranged alternately on either side of the chain, and which are adapted to follow the displacement of the rods 9a-9f, and a translating means responsive to variations in the path of the chain. Each rod 109 has a collar 103 which co-operates with a lever 127 pivoted on a rod 125 and carrying a chain engaging roller 131, rollers 131a, c, e being arranged below the chain and rollers 131b, d, f above. Levers 127a, c, e engage the collars 103a, c, e with abutments 129a, c, e, and levers 127b, d, f engage collars 103b, d, f with abutments 129b, d, f, the arrangement being such that for upward movement of all the collars rollers 131a, c, e move downwards and rollers 131b, d, f move upwards so displacing an indicator mark B on the chain along a fixed graduated plate C. The shaft 125 together with all the levers 127 is vertically adjustable on rods 112, 113, 115, 119 and, in addition, each lever is individually adjustable by adjusting the length of the associated abutment 129. One end of the chain is anchored at 133 and the other end is connected at 41 with a sector 37, Fig. 2, freely pivoted on a shaft 31 and having an arm 45 secured to an adjustable abutment 47 which co-operates with an arm 49 secured to the shaft and carrying an adjustable guide roller 55. An increase in load allows the chain 21 to be moved in the direction of the arrow A by a spring (not shown), which biasses the shaft 31 clockwise, and the consequent rotation of the shaft causes a number of rotary switch operating cams arranged coaxially on the shaft 31, to operate a number of taping switches connected with a variable resistance 97, Fig. 10, so that the time constant of a brake releasing circuit 161 is varied with the load, and thus, as in Specification 548,772, [Group XXXVII], after closing contacts M<1> a controlled time delay can be effected such that the hoisting motor is allowed to develop sufficient torque to lift the loaded car before the current in the brake releasing coil 18a has built up sufficiently to release the brake. The variable resistance may also be used to vary the resistance of the discharge circuit of the release coil of the brake so that the brake is applied at a time determined by the load in order that accurate floor levelling may be effected regardless of the load. An extra switch operating cam (not shown), may be fitted to the shaft 31 and arranged to close contacts controlling a byepass relay when the maximum load is being carried, this relay is then arranged to prevent stopping of the car in response to hall push buttons.